As we move on, now, to a medical alert this morning. For the first time, the mysterious and potentially deadly mers virus has been passed from one person to another on American soil. This is the third person found to have the infection here. So, let's bring in ABC's Dr. Rich Besser. Doctor, good morning. How did this person get mers? About two weeks ago we talked about the first case in an American worker who worked in Saudi Arabia. As part of the investigation, they tested everyone who had close contact with him. And the person they found just yesterday was one of those people who had contact. But the contact wasn't extreme. He had two meetings with the Indiana worker. The longest was for 40 minutes and involved face-to-face contact and a handshake. Good news is, he's well. The fact he got it just from a handshake concern you? That's very concerning. The big focus has been on close contact. Health care workers, family members who live together. Here, 40 minutes and aa handshake is more than we thought. We do know the virus can be deadly. Should we be worried about this? If you're going to the Arabian peninsula, you want to follow the guidelines for protection. They're going to check everyone who came in contact with the new case, did they pick up the infection? Had something changed? I don't think people need to be alarmed about this. But it's very good they're checking to see have there been changes and do we need to take different kinds of protection. It's a relief to hear you say we shouldn't get alarmed by this. Rich, thank you very much. Appreciate it.

This transcript has been automatically generated and may not be 100% accurate.

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